OPC UA Client Connection Limit

I’ve seen some stuff suggesting the client limit to the OPC UA server is capped at 100 clients and can’t be changed. Is this a licensing issue? Is there any way to increase this limit?


What version of Ignition are you using?

Version: 8.1.4 (b2021040109)

Okay, yes, in that case it looks like in all versions of Ignition 8.x the server has a default limit of 100 sessions. It’s not a licensing issue, but it’s also not currently configurable.

What’s your use case? How many clients/sessions do you intend to connect and what would they be doing?

We have a bunch of individual machines using the server to communicate with a single Rockwell PLC. Each machine only has 10-20 tags.


So just to make sure I’m clear - each of these individual machines has its own OPC UA client that is making a connection to an Ignition OPC UA server, which in turn is connected to a single PLC.

I can make a ticket to expose session limit somehow. I don’t know how much a “bunch” is or how well the server will scale as you increase the number of sessions, but at only 10-20 tags per client I suspect you’ll be okay…

That’s correct. Sorry - “a bunch” will probably end up being 150-200 devices. In the short term, we only need <50 devices, but we already have more than 100 trying to connect (as the machines are updated, they automatically connect to the server even if we aren’t ready for the connection). This was taking slots from things we need currently. So in the meantime I was able to reject those connections via ufw, but long term we will need everything connected. If it doesn’t scale well, we’d look for another solution.

I fast tracked this because it’s a super easy change and I’m curious. It should land in a nightly release sometime soon, once it has gone through QA.

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Just to clarify, does that mean in 8.x you can’t configure more than 100 OPC UA clients on a single server? Because I just realized that I will need to scale to 100+ clients at some point. And can you point me to anything in the documentation that states the limitations? I can’t see anything after a cursory glance.

The Ignition OPC-UA server is limited to 100 active client connections.
An individual Ignition Gateway only acts as one client - it’s not 1 UA client per Vision client, or Perspective session.

Argghh … I think I am panicking with misunderstanding the terminology. In my case I want to have a single GW talking to 100+ PLCs, so 100+ configured OPC UA Clients on that GW

No problem. You can have as many OPC UA client connections as you want.

I’m assuming you know what you’re talking about here and these are modern PLCs that actually have an onboard OPC UA server. An EtherNet/IP connection to a Logix PLC using one of our drivers is not an OPC UA connection, for example.

Definitely a PLC with a built in server. But modern? :rofl:

It’s all relative in this industry…

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Also, FWIW, having a lot of outgoing OPC UA client connections is something I expect to scale well.

Last year I tested 5,000 connections with 100 tags each, updating @ 1s (500,000 updates/sec). The biggest problem at that scale is our internal DB and config pages aren’t built for it, but at the OPC UA layer it’s fine.

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